Monte Carlo Simulation of Light Scattering in Paper

Abstract: Paper is a very complex optical material. Analytical models explaining some of the optical properties of mpaper exist, but they often rely on bold simplifications. Monte Carlo simulation models are less constrained and allow for a greater degree of complexity. Grace is a three-dimensional light scattering simulation tool for paper, previously implemented in Matlab. During this project, the basesheet model was implemented in C++. This model simulates a layer containing a network of wood fibers and filler material. The new implementation makes simulations much faster. In addition, some new features and enhancements were developed. Wavelength dependency of parameters and fluorescence were implemented and tested. A problem with Grace was that there was no simple way to calculate the grammage of the simulated paper. A method to analytically determine grammage was developed so that the user has complete control over the grammage of the fiber network. Modifications were made to improve light scattering at the pore boundaries. A new feature was also added to study how the fibers’ and fillers’ geometry affects the light scattering at the paper surface.